Covariant feature detectors - Definition. More...
Data Structures | |
struct | _VlCovDet |
Covariant feature detector. More... | |
Functions | |
static int | _vl_resize_buffer (void **buffer, vl_size *bufferSize, vl_size targetSize) |
Reallocate buffer. More... | |
static int | _vl_enlarge_buffer (void **buffer, vl_size *bufferSize, vl_size targetSize) |
Enlarge buffer. More... | |
vl_size | vl_find_local_extrema_3 (vl_index **extrema, vl_size *bufferSize, float const *map, vl_size width, vl_size height, vl_size depth, double threshold) |
Find the extrema of a 3D function. More... | |
vl_size | vl_find_local_extrema_2 (vl_index **extrema, vl_size *bufferSize, float const *map, vl_size width, vl_size height, double threshold) |
Find extrema in a 2D function. More... | |
vl_bool | vl_refine_local_extreum_3 (VlCovDetExtremum3 *refined, float const *map, vl_size width, vl_size height, vl_size depth, vl_index x, vl_index y, vl_index z) |
Refine the location of a local extremum of a 3D map. More... | |
vl_bool | vl_refine_local_extreum_2 (VlCovDetExtremum2 *refined, float const *map, vl_size width, vl_size height, vl_index x, vl_index y) |
Refine the location of a local extremum of a 2D map. More... | |
VlCovDet * | vl_covdet_new (VlCovDetMethod method) |
Create a new object instance. More... | |
void | vl_covdet_reset (VlCovDet *self) |
Reset object. More... | |
void | vl_covdet_delete (VlCovDet *self) |
Delete object instance. More... | |
int | vl_covdet_append_feature (VlCovDet *self, VlCovDetFeature const *feature) |
Append a feature to the internal buffer. More... | |
int | vl_covdet_put_image (VlCovDet *self, float const *image, vl_size width, vl_size height) |
Detect features in an image. More... | |
static void | _vl_det_hessian_response (float *hessian, float const *image, vl_size width, vl_size height, double step, double sigma) |
Scaled derminant of the Hessian filter. More... | |
static void | _vl_harris_response (float *harris, float const *image, vl_size width, vl_size height, double step, double sigma, double sigmaI, double alpha) |
Scale-normalised Harris response. More... | |
static void | _vl_dog_response (float *dog, float const *level1, float const *level2, vl_size width, vl_size height) |
Difference of Gaussian. More... | |
void | vl_covdet_detect (VlCovDet *self) |
Detect scale-space features. More... | |
vl_bool | vl_covdet_extract_patch_helper (VlCovDet *self, double *sigma1, double *sigma2, float *patch, vl_size resolution, double extent, double sigma, double A_ [4], double T_ [2], double d1, double d2) |
Helper for extracting patches. More... | |
vl_bool | vl_covdet_extract_patch_for_frame (VlCovDet *self, float *patch, vl_size resolution, double extent, double sigma, VlFrameOrientedEllipse frame) |
Helper for extracting patches. More... | |
int | vl_covdet_extract_affine_shape_for_frame (VlCovDet *self, VlFrameOrientedEllipse *adapted, VlFrameOrientedEllipse frame) |
Extract the affine shape for a feature frame. More... | |
void | vl_covdet_extract_affine_shape (VlCovDet *self) |
Extract the affine shape for the stored features. More... | |
VlCovDetFeatureOrientation * | vl_covdet_extract_orientations_for_frame (VlCovDet *self, vl_size *numOrientations, VlFrameOrientedEllipse frame) |
Extract the orientation(s) for a feature. More... | |
void | vl_covdet_extract_orientations (VlCovDet *self) |
Extract the orientation(s) for the stored features. More... | |
VlCovDetFeatureLaplacianScale * | vl_covdet_extract_laplacian_scales_for_frame (VlCovDet *self, vl_size *numScales, VlFrameOrientedEllipse frame) |
Extract the Laplacian scale(s) for a feature frame. More... | |
void | vl_covdet_extract_laplacian_scales (VlCovDet *self) |
Extract the Laplacian scales for the stored features. More... | |
void | vl_covdet_drop_features_outside (VlCovDet *self, double margin) |
Drop features (partially) outside the image. More... | |
vl_bool | vl_covdet_get_transposed (VlCovDet const *self) |
Get wether images are passed in transposed. More... | |
void | vl_covdet_set_transposed (VlCovDet *self, vl_bool t) |
Set the index of the first octave. More... | |
double | vl_covdet_get_edge_threshold (VlCovDet const *self) |
Get the edge threshold. More... | |
void | vl_covdet_set_edge_threshold (VlCovDet *self, double edgeThreshold) |
Set the edge threshold. More... | |
double | vl_covdet_get_peak_threshold (VlCovDet const *self) |
Get the peak threshold. More... | |
void | vl_covdet_set_peak_threshold (VlCovDet *self, double peakThreshold) |
Set the peak threshold. More... | |
double | vl_covdet_get_laplacian_peak_threshold (VlCovDet const *self) |
Get the Laplacian peak threshold. More... | |
void | vl_covdet_set_laplacian_peak_threshold (VlCovDet *self, double peakThreshold) |
Set the Laplacian peak threshold. More... | |
vl_index | vl_covdet_get_first_octave (VlCovDet const *self) |
Get the index of the first octave. More... | |
void | vl_covdet_set_first_octave (VlCovDet *self, vl_index o) |
Set the index of the first octave. More... | |
vl_size | vl_covdet_get_num_octaves (VlCovDet const *self) |
Get the max number of octaves. More... | |
double | vl_covdet_get_base_scale (VlCovDet const *self) |
Get the GSS base scale. More... | |
void | vl_covdet_set_num_octaves (VlCovDet *self, vl_size o) |
Set the max number of octaves. More... | |
void | vl_covdet_set_base_scale (VlCovDet *self, double s) |
Set the GSS base scale. More... | |
void | vl_covdet_set_max_num_orientations (VlCovDet *self, vl_size m) |
Set the max number of orientations. More... | |
vl_size | vl_covdet_get_octave_resolution (VlCovDet const *self) |
Get the octave resolution. More... | |
void | vl_covdet_set_octave_resolution (VlCovDet *self, vl_size r) |
Set the octave resolutuon. More... | |
vl_bool | vl_covdet_get_aa_accurate_smoothing (VlCovDet const *self) |
Get whether affine adaptation uses accurate smoothing. More... | |
void | vl_covdet_set_aa_accurate_smoothing (VlCovDet *self, vl_bool x) |
Set whether affine adaptation uses accurate smoothing. More... | |
vl_size | vl_covdet_get_max_num_orientations (VlCovDet const *self) |
Get the max number of orientations. More... | |
double | vl_covdet_get_non_extrema_suppression_threshold (VlCovDet const *self) |
Get the non-extrema suppression threshold. More... | |
void | vl_covdet_set_non_extrema_suppression_threshold (VlCovDet *self, double x) |
Set the non-extrema suppression threshod. More... | |
vl_size | vl_covdet_get_num_non_extrema_suppressed (VlCovDet const *self) |
Get the number of non-extrema suppressed. More... | |
vl_size | vl_covdet_get_num_features (VlCovDet const *self) |
Get number of stored frames. More... | |
void * | vl_covdet_get_features (VlCovDet *self) |
Get the stored frames. More... | |
VlScaleSpace * | vl_covdet_get_gss (VlCovDet const *self) |
Get the Gaussian scale space. More... | |
VlScaleSpace * | vl_covdet_get_css (VlCovDet const *self) |
Get the cornerness measure scale space. More... | |
vl_size const * | vl_covdet_get_laplacian_scales_statistics (VlCovDet const *self, vl_size *numScales) |
Get the number of features found with a certain number of scales. More... | |
vl_bool | vl_covdet_get_allow_padded_warping (VlCovDet const *self) |
Get wether to compute padded warped patches. More... | |
void | vl_covdet_set_allow_padded_warping (VlCovDet *self, vl_bool t) |
Set wether to compute padded warped patches. More... | |
Detailed Description
Function Documentation
◆ _vl_det_hessian_response()
|
static |
- Parameters
-
hessian output image. image input image. width image width. height image height. step image sampling step (pixel size). sigma Gaussian smoothing of the input image.
◆ _vl_dog_response()
|
static |
- Parameters
-
dog output image. level1 input image at the smaller Gaussian scale. level2 input image at the larger Gaussian scale. width image width. height image height.
◆ _vl_enlarge_buffer()
- Parameters
-
buffer bufferSize targetSize
- Returns
- error code
◆ _vl_harris_response()
|
static |
- Parameters
-
harris output image. image input image. width image width. height image height. step image sampling step (pixel size). sigma Gaussian smoothing of the input image. sigmaI integration scale. alpha factor in the definition of the Harris score.
◆ _vl_resize_buffer()
- Parameters
-
buffer bufferSize targetSize
- Returns
- error code
◆ vl_covdet_append_feature()
int vl_covdet_append_feature | ( | VlCovDet * | self, |
VlCovDetFeature const * | feature | ||
) |
- Parameters
-
self object. feature a pointer to the feature to append.
- Returns
- status.
The feature is copied. The function may fail with status
equal to VL_ERR_ALLOC if there is insufficient memory.
◆ vl_covdet_delete()
void vl_covdet_delete | ( | VlCovDet * | self | ) |
- Parameters
-
self object.
◆ vl_covdet_detect()
void vl_covdet_detect | ( | VlCovDet * | self | ) |
- Parameters
-
self object.
This function runs the configured feature detector on the image that was passed by using vl_covdet_put_image.
◆ vl_covdet_drop_features_outside()
void vl_covdet_drop_features_outside | ( | VlCovDet * | self, |
double | margin | ||
) |
- Parameters
-
self object. margin geometric marging.
The feature extent is defined by maring
. A bounding box in the normalised feature frame containin a circle of radius maring is created and mapped to the image by the feature frame transformation. Then the feature is dropped if the bounding box is not contained in the image.
For example, setting margin
to zero drops a feature only if its center is not contained.
Typically a valua of margin
equal to 1 or 2 is used.
◆ vl_covdet_extract_affine_shape()
void vl_covdet_extract_affine_shape | ( | VlCovDet * | self | ) |
- Parameters
-
self object.
This function may discard features for which no affine shape can reliably be detected.
◆ vl_covdet_extract_affine_shape_for_frame()
int vl_covdet_extract_affine_shape_for_frame | ( | VlCovDet * | self, |
VlFrameOrientedEllipse * | adapted, | ||
VlFrameOrientedEllipse | frame | ||
) |
- Parameters
-
self object. adapted the shape-adapted frame. frame the input frame.
- Returns
- VL_ERR_OK if affine adaptation is successful.
This function may fail if adaptation is unsuccessful or if memory is insufficient.
◆ vl_covdet_extract_laplacian_scales()
void vl_covdet_extract_laplacian_scales | ( | VlCovDet * | self | ) |
- Parameters
-
self object.
Note that, since more than one orientation can be detected for each feature, this function may create copies of them, one for each orientation.
◆ vl_covdet_extract_laplacian_scales_for_frame()
VlCovDetFeatureLaplacianScale* vl_covdet_extract_laplacian_scales_for_frame | ( | VlCovDet * | self, |
vl_size * | numScales, | ||
VlFrameOrientedEllipse | frame | ||
) |
- Parameters
-
self object. numScales the number of detected scales. frame pose of the feature.
- Returns
- an array of detected scales.
The function returns NULL
if memory is insufficient.
◆ vl_covdet_extract_orientations()
void vl_covdet_extract_orientations | ( | VlCovDet * | self | ) |
- Parameters
-
self object.
Note that, since more than one orientation can be detected for each feature, this function may create copies of them, one for each orientation.
◆ vl_covdet_extract_orientations_for_frame()
VlCovDetFeatureOrientation* vl_covdet_extract_orientations_for_frame | ( | VlCovDet * | self, |
vl_size * | numOrientations, | ||
VlFrameOrientedEllipse | frame | ||
) |
- Parameters
-
self object. numOrientations the number of detected orientations. frame pose of the feature.
- Returns
- an array of detected orientations with their scores.
The returned array is a matrix of size \( 2 \times n \) where n is the number of detected orientations.
The function returns NULL
if memory is insufficient.
◆ vl_covdet_extract_patch_for_frame()
vl_bool vl_covdet_extract_patch_for_frame | ( | VlCovDet * | self, |
float * | patch, | ||
vl_size | resolution, | ||
double | extent, | ||
double | sigma, | ||
VlFrameOrientedEllipse | frame | ||
) |
- Parameters
-
self object. patch buffer. resolution patch resolution. extent patch extent. sigma desired smoothing in the patch frame. frame feature frame.
The function considers a patch of extent [-extent,extent]
on each side, with a side counting 2*resolution+1
pixels. In attempts to extract from the scale space a patch based on the affine warping specified by frame in such a way that the resulting smoothing of the image is sigma (in the patch frame).
The transformation is specified by the matrices A
and T
embedded in the feature frame. Note that this transformation maps pixels from the patch frame to the image frame.
◆ vl_covdet_extract_patch_helper()
vl_bool vl_covdet_extract_patch_helper | ( | VlCovDet * | self, |
double * | sigma1, | ||
double * | sigma2, | ||
float * | patch, | ||
vl_size | resolution, | ||
double | extent, | ||
double | sigma, | ||
double | A_[4], | ||
double | T_[2], | ||
double | d1, | ||
double | d2 | ||
) |
- Parameters
-
self object. [out] sigma1 actual patch smoothing along the first axis. [out] sigma2 actual patch smoothing along the second axis. patch buffer. resolution patch resolution. extent patch extent. sigma desired smoothing in the patch frame. A_ linear transfomration from patch to image. T_ translation from patch to image. d1 first singular value A. d2 second singular value of A.
◆ vl_covdet_get_aa_accurate_smoothing()
- Parameters
-
self object.
- Returns
true
if accurate smoothing is used.
◆ vl_covdet_get_allow_padded_warping()
- Parameters
-
self object.
- Returns
- whether padded warped patches are computed.
◆ vl_covdet_get_base_scale()
double vl_covdet_get_base_scale | ( | VlCovDet const * | self | ) |
- Parameters
-
self object.
- Returns
- The base scale.
◆ vl_covdet_get_css()
VlScaleSpace* vl_covdet_get_css | ( | VlCovDet const * | self | ) |
- Returns
- cornerness measure scale space.
A cornerness measure scale space exists only after calling vl_covdet_detect. Otherwise the function returns NULL
.
◆ vl_covdet_get_edge_threshold()
double vl_covdet_get_edge_threshold | ( | VlCovDet const * | self | ) |
- Parameters
-
self object.
- Returns
- the edge threshold.
◆ vl_covdet_get_features()
void* vl_covdet_get_features | ( | VlCovDet * | self | ) |
- Returns
- frames stored in the detector.
◆ vl_covdet_get_first_octave()
- Parameters
-
self object.
- Returns
- index of the first octave.
◆ vl_covdet_get_gss()
VlScaleSpace* vl_covdet_get_gss | ( | VlCovDet const * | self | ) |
- Returns
- Gaussian scale space.
A Gaussian scale space exists only after calling vl_covdet_put_image. Otherwise the function returns NULL
.
◆ vl_covdet_get_laplacian_peak_threshold()
double vl_covdet_get_laplacian_peak_threshold | ( | VlCovDet const * | self | ) |
- Parameters
-
self object.
- Returns
- the Laplacian peak threshold.
This parameter affects only the detecors using the Laplacian scale selectino method such as Harris-Laplace.
◆ vl_covdet_get_laplacian_scales_statistics()
vl_size const* vl_covdet_get_laplacian_scales_statistics | ( | VlCovDet const * | self, |
vl_size * | numScales | ||
) |
- Parameters
-
self object. numScales length of the histogram (out).
- Returns
- histogram.
Calling this function makes sense only after running a detector that uses the Laplacian as a secondary measure for scale detection
◆ vl_covdet_get_max_num_orientations()
- Parameters
-
self object.
- Returns
- maximal number of orientations.
◆ vl_covdet_get_non_extrema_suppression_threshold()
double vl_covdet_get_non_extrema_suppression_threshold | ( | VlCovDet const * | self | ) |
- Parameters
-
self object.
- Returns
- threshold.
◆ vl_covdet_get_num_features()
- Returns
- number of frames stored in the detector.
◆ vl_covdet_get_num_non_extrema_suppressed()
- Parameters
-
self object.
- Returns
- number.
◆ vl_covdet_get_num_octaves()
- Parameters
-
self object.
- Returns
- maximal number of octaves.
◆ vl_covdet_get_octave_resolution()
- Parameters
-
self object.
- Returns
- octave resolution.
◆ vl_covdet_get_peak_threshold()
double vl_covdet_get_peak_threshold | ( | VlCovDet const * | self | ) |
- Parameters
-
self object.
- Returns
- the peak threshold.
◆ vl_covdet_get_transposed()
- Parameters
-
self object.
- Returns
- whether images are transposed.
◆ vl_covdet_new()
VlCovDet* vl_covdet_new | ( | VlCovDetMethod | method | ) |
- Parameters
-
method method for covariant feature detection.
- Returns
- new covariant detector.
◆ vl_covdet_put_image()
- Parameters
-
self object. image image to process. width image width. height image height.
- Returns
- status.
width and height must be at least one pixel. The function fails by returing VL_ERR_ALLOC if the memory is insufficient.
◆ vl_covdet_reset()
void vl_covdet_reset | ( | VlCovDet * | self | ) |
- Parameters
-
self object.
This function removes any buffered features and frees other internal buffers.
◆ vl_covdet_set_aa_accurate_smoothing()
- Parameters
-
self object. x whether accurate smoothing should be usd.
◆ vl_covdet_set_allow_padded_warping()
- Parameters
-
self object. t whether padded warped patches are computed.
◆ vl_covdet_set_base_scale()
void vl_covdet_set_base_scale | ( | VlCovDet * | self, |
double | s | ||
) |
- Parameters
-
self object. s the base scale.
Calling this function resets the detector.
◆ vl_covdet_set_edge_threshold()
void vl_covdet_set_edge_threshold | ( | VlCovDet * | self, |
double | edgeThreshold | ||
) |
- Parameters
-
self object. edgeThreshold the edge threshold.
The edge threshold must be non-negative.
◆ vl_covdet_set_first_octave()
- Parameters
-
self object. o index of the first octave.
Calling this function resets the detector.
◆ vl_covdet_set_laplacian_peak_threshold()
void vl_covdet_set_laplacian_peak_threshold | ( | VlCovDet * | self, |
double | peakThreshold | ||
) |
- Parameters
-
self object. peakThreshold the Laplacian peak threshold.
The peak threshold must be non-negative.
◆ vl_covdet_set_max_num_orientations()
- Parameters
-
self object. m the max number of orientations.
Calling this function resets the detector.
◆ vl_covdet_set_non_extrema_suppression_threshold()
void vl_covdet_set_non_extrema_suppression_threshold | ( | VlCovDet * | self, |
double | x | ||
) |
- Parameters
-
self object. x threshold.
◆ vl_covdet_set_num_octaves()
- Parameters
-
self object. o max number of octaves.
Calling this function resets the detector.
◆ vl_covdet_set_octave_resolution()
- Parameters
-
self object. r octave resoltuion.
Calling this function resets the detector.
◆ vl_covdet_set_peak_threshold()
void vl_covdet_set_peak_threshold | ( | VlCovDet * | self, |
double | peakThreshold | ||
) |
- Parameters
-
self object. peakThreshold the peak threshold.
The peak threshold must be non-negative.
◆ vl_covdet_set_transposed()
- Parameters
-
self object. t whether images are transposed.
◆ vl_find_local_extrema_2()
vl_size vl_find_local_extrema_2 | ( | vl_index ** | extrema, |
vl_size * | bufferSize, | ||
float const * | map, | ||
vl_size | width, | ||
vl_size | height, | ||
double | threshold | ||
) |
- Parameters
-
extrema buffer containing the found extrema (in/out). bufferSize size of the extrema buffer in bytes (in/out). map a 3D array representing the map. width of the map. height of the map. threshold minumum extremum value.
- Returns
- number of extrema found.
An extremum contains 2 vl_index values; they are arranged sequentially.
The function can reuse an already allocated buffer if extrema and bufferSize are initialized on input. It may have to realloc the memory if the buffer is too small.
◆ vl_find_local_extrema_3()
vl_size vl_find_local_extrema_3 | ( | vl_index ** | extrema, |
vl_size * | bufferSize, | ||
float const * | map, | ||
vl_size | width, | ||
vl_size | height, | ||
vl_size | depth, | ||
double | threshold | ||
) |
- Parameters
-
extrema buffer containing the extrema found (in/out). bufferSize size of the extrema buffer in bytes (in/out). map a 3D array representing the map. width of the map. height of the map. depth of the map. threshold minumum extremum value.
- Returns
- number of extrema found.
- See also
- vl_refine_local_extreum_2.
◆ vl_refine_local_extreum_2()
vl_bool vl_refine_local_extreum_2 | ( | VlCovDetExtremum2 * | refined, |
float const * | map, | ||
vl_size | width, | ||
vl_size | height, | ||
vl_index | x, | ||
vl_index | y | ||
) |
- Parameters
-
refined refined extremum (out). map a 2D array representing the map. width of the map. height of the map. x initial x position. y initial y position.
- Returns
- a flat indicating whether the extrema refinement was stable.
◆ vl_refine_local_extreum_3()
vl_bool vl_refine_local_extreum_3 | ( | VlCovDetExtremum3 * | refined, |
float const * | map, | ||
vl_size | width, | ||
vl_size | height, | ||
vl_size | depth, | ||
vl_index | x, | ||
vl_index | y, | ||
vl_index | z | ||
) |
- Parameters
-
refined refined extremum (out). map a 3D array representing the map. width of the map. height of the map. depth of the map. x initial x position. y initial y position. z initial z position.
- Returns
- a flat indicating whether the extrema refinement was stable.